As gross domestic product (GDP) increases, people put more emphasis on a higher living standard and like products having artistic and fashionable shapes. People buying articles for daily use take into consideration whether the articles are durable or not, are practicable or not and have an artistic and fashionable shape or not.
With reference to FIG. 1, a conventional bamboo chair (2) with a fashionable and smooth shape was designed and manufactured, comprises multiple curved elements aligning with each other and has an upper rear curve (21), an upper front curve (22) and a lower front curve (23). However, the bamboo chair (2) cannot bear a large person's weight because the upper front curve (22) will break when a large person sits on the bamboo chair (2). When the upper front curve (22) breaks, a person sitting on the bamboo chair (2) will likely be injured. Consequently, the bamboo chair (2) is not durable and practical and is not a good chair even though it has a fashionable and smooth shape